Electron is a software framework that essentially lets you build desktop applications using web stuff (i.e. HTML, Javascript). As such, each Electron app comes bundled with chromium, an embedded browser that is the basis of Google Chrome.

The problem is that, much like Chrome, Electron hogs a lot of RAM and other resources. And since each Electron app uses a separate instance of Chromium, the problem compounds (as opposed to having each app as a tab in your browser, where they can share resources from one single Chrome instance).

So the problem is, imagine having to run a separate instance of Chrome for each program you use. That's why people don't like Electron.

Godot is a game engine, but it's also fairly capable for making desktop applications. This meme is comparing Godot, which bundles a complete game engine in each app, with Electron, which bundles a complete browser.